Balloon angioplasty procedures have been used in recent years with increasing success in the treatment of obstructed arteries, such as the coronary arteries. The procedure involves advancing a catheter having a special balloon at its distal end to the location of the stenosis. The balloon portion of the catheter is placed, in its deflated condition, in the stenosis and then is inflated under high pressure to compress radially and outwardly the biological material such as plaque which forms the stenosis. A balloon dilatation system of this type is illustrated in Gruntzig U.S. Pat. No. 4,195,637. In those situations in which balloon angioplasty can be used, its successful use avoids the greater risk of complex and expensive bypass surgery.
Not all arterial stenoses are treatable by balloon angioplasty. Among the types of vascular obstructions which have not been treatable with the angioplasty technology are those in which the passage through the stenosis is so narrow that the balloon angioplasty catheter cannot be inserted into the stenosis, even when the balloon is in its collapsed, deflated condition. Thus, where the opening in a stenosis was only enough to permit passage of a guide wire, but not enough to permit passage of a deflated angioplasty balloon, the procedure could not be performed. Until the present invention, such conditions disqualified the patient from receiving the potential benefits of the angioplasty technique. Instead, such conditions required bypass surgery.
Also among the difficulties encountered in the angioplasty technique has been in the advancement and placement of the dilatation balloon catheter in the intended branch of the arterial tree so that it can be advanced into the stenosis to be treated. Difficulties often are encountered in guiding the catheter to the obstructed branch or portion of the arterial tree.
It is among the primary objects of the invention to provide a dilatation catheter system including a microdilatation probe which enables such very narrow stenoses to be treated with the balloon angioplasty technique, and in a manner in which the catheter can be guided accurately.